What are best medicines and trestment for GERD and preventing ulcer formation?

Omeprazole, but... The hallmark symptoms are heartburn and acid regurgitation, and there can be metallic or sour taste in the mouth, bad breath, and even cough, laryngitis and asthma symptoms. Omeprazole (aka Prilosec) OTC taken once a day for 14 days should treat routine symptoms. Any recurrence or persistence of symptoms needs to be evaluated by your doctor.